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High-entropy (Ti0.2Zr0.2Hf0.2Nb0.2Ta0.2)C ceramics, with different contents (0, 5, 10, and 20 vol.%) of SiC whiskers (SiCw), were fabricated by spark plasma sintering using raw powders synthesized via carbothermal reduction. The application of a uniaxial compaction force led to texture development of the SiCw within the (Ti0.2Zr0.2Hf0.2Nb0.2Ta0.2)C matrix. Fracture toughness increased with the increase in SiCw content, while Vickers hardness remains almost unchanged. The toughness of (Ti0.2Zr0.2Hf0.2Nb0.2Ta0.2)C-20 vol.% SiCw ceramics reached 4.3 ± 0.3 MPa∙m1/2, which was approximately 43% higher than that of the monolithic (Ti0.2Zr0.2Hf0.2Nb0.2Ta0.2)C ceramic (3.0 ± 0.2 MPa∙m1/2). The main toughening mechanisms were attributed to crack deflection, whisker debonding, and whisker pullout.

Silicon nitride (Si3N4) ceramic cutting tool with excellent cutting performance was successfully achieved through the control of phase composition and microstructure. The hardness of the tool with 49.7 wt% and 4.9 wt% α-Si3N4 is ∼20.1 GPa and ∼17.5 GPa, respectively. In continuous cutting of cast iron, the tool life significantly increases from ∼1200 m to ∼2400 m when α-Si3N4 content increases from 4.9 wt% to 49.7 wt%, respectively. The longer tool life is attributed to a better abrasive and adhesive wear resistance of α-Si3N4 phase. In addition, the chemical reaction between Si3N4 ceramic tool and cast iron would lead to the formation of an amorphous oxide layer on wear surface. It was noted that the higher α-Si3N4 content would lead to greater probability of chipping due to lower fracture toughness. Therefore, high-performance Si3N4 ceramic tool could be achieved using an α-Si3N4 matrix ceramic reinforced with elongated β-Si3N4 phase.

宣城矿集区是长江中下游成矿带内新提出的矿集区，近年来取得了重大的找矿突破，尤其是大型斑岩型铜金矿的发现使宣城矿集区逐渐成为研究热点。宣城矿集区一系列的斑岩-矽卡岩矿床均与早白垩世侵入体密切相关。荞麦山铜钨矿床是区内典型的矽卡岩矿床，矿床形成与花岗闪长斑岩密切相关，且花岗闪长斑岩发育较多的暗色包体。确定暗色包体的成因有助于深入理解含矿岩体的岩浆演化过程及成矿意义。本次工作以荞麦山矿床花岗闪长斑岩和暗色包体作为研究对象进行U-Pb同位素年代学、岩石及矿物地球化学、全岩Sr-Nd、锆石Hf-O同位素地球化学分析，探讨暗色包体及成矿岩体的源区、岩浆演化过程及其对成矿的意义。暗色包体的形成时代为141Ma（MSWD=0.8），（87Sr/86Sr）i值为0.7059~0.7069，eNd（t）值为-6.0~-9.2，eHf（t）值为-12.7~-5.8，δ18O值为5.8‰~7.7‰；寄主岩石形成时代为140Ma（MSWD=0.3），（87Sr/86Sr）i值为0.7061~0.7064，eNd（t）值为-8.7~-7.7，eHf（t）值为-12.1~-8.1，δ18O值为5.6‰~7.4‰。此外，暗色包体与寄主岩石主要氧化物含量与SiO2含量呈线性负相关趋势、微量元素特征相似和寄主岩石斜长石斑晶的不平衡结构及捕掳晶的发现指示荞麦山暗色包体为岩浆混合成因，花岗闪长斑岩为起源于富集地幔的岩浆与壳源岩浆混合成的母岩浆侵位而来，同时幔源岩浆和壳源岩浆的混合也分别提供了成矿金属元素铜和钨，最终形成了铜钨共生的荞麦山矿床。